Mechanical pencil with lead advancing means



Feb. 3, 1953 R. B. hoHNsoN MECHANICAL PENCIL WITH LEAD ADVANCING MEANS Filed Jan. 16. 194B Y /lvillini/5451515415/ mit n Patented Feb. 3, 1953 MECHANICAL PENCIL WITH LEAD ADVANCING MEANS Rcynold B. Johnson, Binghamton, N. Y., assigner to International Business Machines Corporation, New York, N. Y., a corporation of New York Application January 16, 1948, Serial No. 2,627

7 Claims.

This invention relates .to an improved mechanical pencil construction `and in particular to means for advancing or feeding the lead to operative writing position as needed.

It is a principal object of the invention to provide an improved feeding means for the lead of a mechanical pencil wherein the lead is fed forward by a positive pushing action of the thumb exerted in an axial direction.

It is a further object of the invention to provide an improved feed means for the lead of a mechanical pencil which will feed the lead by a depressed thumb action without damage to the lead and which is especially adapted to the feeding of soft leads such as mark sensing leads used in connection with mark sensed records.

A further object of the invention is to provide a feed mechanism for a mechanical pencil which positively advances the lead an equal distance each time the eraser end of the pencil is depressed and which mechanism does not employ chuck jaws or the like which dig into the lead 4and damage the same as is the case with many prior art instances of thumb operated pencils.

Other objects will appear as the description proceeds.

In the `accompanying drawings which form a part of this application,

Figure 1 is a longitudinal sectional view through the improved semi-automatic feed mechanical pencil;

Figure 2 is an enlarged plan view of the' lead clutch supporting mechanism including Ithe follower rod 30 associated therewith;

Figure 3 is a detailed sectional View of the rear end of the spirally slotted guide tubing for the lead clutch supporting mechanism with a single clutch tooth formed thereon, and an eraser supporting tubing fixed about the end of said guide tubing; and

Figure 4 is a side elevation of the multiple toothed clutch collar rigidly secured to the outer end of the longitudinally split feed tubing.

Like characters of reference are used throughout the following specification and the accompanying drawings to designate corresponding parts.

The improved semi-automatic feed mechanical pencil comprises a conventional outer barrel or 4casing I having a tapered inner end 2 which is formed with a restricted passage 3 provided with an inwardly directed locking head 4 at its forward end, and a shoulder 5 formed at its rear end. The outer end of the barrel or casing I is open as at 6 for purposes hereinafter more fully described. l

A tapered tip 'I is axially bored at 8 and is formed with a cylindrical sleeve portion at its inner end adapted to be received within `the restricted passage 3 in the tapered inner or forward end 2 of the barrel I. The tapered tip 'I is also formed with a peripheral locking groove I0 in which the locking head 4 on the forward end of the barrel I is disposed. It will of course be understood that any other form of connection between the tip 1 and the inner end of the barrel 2, such as a screw threaded connection, or the like, may be used if desired, without departing from the spirit of the invention to be hereinafter described.

The rear end of the axial bore 8 in the tapered tip 'I is slightly enlarged to rigidly support the forward end of a feed tube II which is longitudinally split as at I2 throughout its length..

A clutch collar I3 is fixed about the outer or opposite end of the feed tube vI I, and is formed with eight forwardly extending clutch teeth I4 on its forward end.

A guide tube I5 formed with a spiral slot I6 throughout its length is mounted for rotation and for longitudinal reciprocating movement labout the longitudinally split feed tubing I I, and is formed with a single clutch tooth Il for cooperative engagement with any of the eight clutch teeth I4 on the forward end of the clutch collar or sleeve I3.

A combined actuating and eraser supporting tube I8 of stepped formationhas its inner or forward end I9 rotatably and reciprocably mounted within the open outer end of the barrel with its extreme forward end 20 disposed about and xed to the outer end of the spirally slotted guide tube I5.

The tube I8 is formed with a peripheral outwardly extending shoulder or stop head normally disposed in spaced relation from the adjacent end E of the barrel I, the same engaging the end 6 of the barrel I, when the eraser 22 disposed in the outer end of the tube I8 is depressed when advancing the lead 23 through the axial bore 8 in the tapered tip 'I of the pencil, as will be more fully explained hereinafter.

A substantially loose -or open coil spring 24 is disposed about spirally slotted guide tube I5 with its forward end bent inwardly at 25 and secured in a notch or bore 26 formed radially in the cylindrical sleeve portion 9 of the tapered tip l, and the outer or opposite end o f the coil spring 24 is secured in an opening 25 formed in the combined actuating and eraser supporting tube I8.

An improved form of lead clutch is provided .a and comprises a section of tubing 26, the same being longitudinally split at 2l and formed with a laterally extending closed ear or pin-like member 28 which may be struck from the material of the tubing 26 and formed into pin-like shape or which may be a separate pin-like element fastened t'o 'the tubing 26 in any suitable manner, such as by soldering, welding, or the like. At a point spaced from the ear or pin-like member 28 the side walls forming the slit 2l in the lead clutch are cut away to form an enlarged substantially rectangular opening in the tubing bounded by the shoulders 32-32 at one end and the shoulder 33 of the transversely extending lip 29 at the rear or inner end of the tubing. A follower rod 30 is slidably disposed in the tubing 26 with its rear end bent at right angles to form a pin 3| extending laterally through the enlarged rectangular opening between the shoulder 32-32 and the lip 23, it being understood that said shoulders and lip will limit the length of movement of 'said rod with Vrespect to said tubing 26 and hence the distance between the laterally extending pin-lilfze elements 25 and 3| is variable within said limits.

The lead `clutch tubing 26 is disposed within the xed feed tube I I with the pin-like elements 23 'and 3| extending laterally through the longitudinal split |2 in the feed tube li and into the spiral slot I 6 inthe guide tube l5 as will be apparent from an inspection 'of Figure 1. The lead clutch tubing 26 is slightly bowed to frictionally hold the same in the desired adjustment within the feed tube Il after the lead 23 has been advanced.

In order to relill the pencil, a piece of lead 23 is inserted through the axial bore 8 in the tapered tip I and through the cylindrical sleeve portion 9 until the inner end of the lead 23 is received in the forward end of the longitudinally split lead clutch tubing 26 and engages the forward end of the rod 30. By rotating the combined actuating and eraser supporting tube i8 in a counterclockwise direction together with the spirally slotted guide tube I fixed thereto While holding the barrel against rotation, the lead clutch tubing 26 will be forced to move upwardly inside the slotted feed tube` II toward the eraser end of the pencil as the pin-like elements 28 and 3| ride inthe spiral slotlt, thus drawing' or retractin'g the lead 23 within 'the pencil.

As the tube I8 is rotated, the coil spring 2li will be simultaneously wound up to a low state of tension. r-he state of tension to which the spring 2li is vthus 'wound will be insuiiicient to overcome the `frictional engagement of the Ilead clutch tubing 26 in the feed tube I I.

The feeding of the lead 23 out of rthe pencil is effected by depressing the eraser 22 which in turn pushes the actuating tube I8 inwardly until the stop head 2| engages the adjacent end 46 of the barrel I. This action also pushes spirally slotted guide tube I5 and the coil spring 2d toward the tip 'I of the pencil, thus causing the spiral slot I6 to carry downwardly therewith the pin-like elements 28 and 3| and hence the lead clutch tubing 26 is moved forwardly in the tube II to feed the lead 23 of the pencil a corresponding distance.

As the actuating tube i8 is depressed, the single tooth Il on the guide tube I5 is moved forwardly out of engagement with the notched forward end of the clutch collar I3, but since Vthe force of the tensioned spring 2li is not suicient to overcome the friction of the lead clutch tubing return movement, additionally :means between said guide and `feed tubes into 26 in the feed tube II, the lead 23 is advanced a distance equal to the distance of movement, of the actuating tube |8 when it is depressed. When the pressure on the actuating tube I8 and eraser 22 is released, the coil spring 24 will cause the spirally slotted guide tube I5 to rotate in a clockwise direction to ride on the pin-like elements 28 and 3l on the split lead clutch tubing 26 until the single tooth I1 on the guide tube I5 again engages one of the clutch teeth I on the clutch collar I3, thereby locking the spirally slotted tube I5 against any further rotary movement. The lead clutch tubing 26 will not move rearwardly with the spirally slotted tube l5 when the actuating tube I8 is released, due to the frictional engagement between the lead clutch tubing 26 and the slotted feed tube I| being greater than the tension of the coil spring 24 that rotates the spirally slotted tube I5.

It will be seen from the foregoing description that'an equal portion of lead 23 is fed out through the tapered tip I by a positive pushing action each time the eraser V22 and the actuating tube V I8 are depressed. The positive pushing action of the lead feed eliminates lthe slipping of the lead 23 that takes place in the feeding mechanisms of many of the conventional mechanical pencils, and particularly in the thumb operated types where the lead is fed by chuck jaws which are moved forward and dig into the lead.

While the preferred embodiment of the instant invention has been illustrated and described, it will be understood that it is not intended to limit the scope of the invention thereto, as many minor changes in detail of construction may be resorted to Without departure from the spirit of the invention.

What I claim as new and useful and desire to secure by United States Letters Patentl is:

l. A mechanical pencil comprising a tubular body tapered at one end, 'a longitudinally slotted feed tube Within said body and xed thereto, a spirally slotted guide tube concentrically disposed with reference to said last mentioned tube and mounted for reciprocal and rotary movement within said tubular body, a lead clutch slidably and frictionally disposed within said longitudinally slotted feed tube and having an offset portion extending laterally of said lead clutch and engaging the slots of the longitudinally slotted feed tube and the spirally slotted guide tube, clutch means between the said feed tube and guide tube to prevent rotation of said spi-rally slotted guide tube relative to said longitudinally slotted feed tube and disengageable by a forward axial movement of said spirally slotted guide tube, said spirally slotted tube by an axial non-rotative movement serving to positively ad- Vance the lead clutch within the longitudinally slotted 4feed tube by engagement of a slot wall of the spirally slotted tube with said offset portion of said lead clutch, thereby advancing said lead clutch against the frictional engagement between said lead clutch and said longitudinally slotted tube, and spring means urging said spi-rally slotted guide tube to rotate relative to said longitudinally slotted feed tube .and -to return said Ispirally slotted guide tube to -its normal position and without disturbing vthe frictional engagement between the lead clutch and the longitudinally slotted feed tube, and .at the end of said urging said clutch engaged position, whereby when said spirally slotted guide tube is depressed in a forward axial direction the lead clutch is positively advanced a corresponding distance in the longitudinally slotted feed tube, and upon return of the spiral-ly slotted tube to original extended position with the clutch means between the said two tubes again fully engaged the pencil is ready for further repeated advancements of the lead clutch by additional depressions' of the spirally slotted guide tube.

2. The subject matter of claim 1 wherein the spring means comprises a torsion spring having one end iixed to the tubular body at the tapered end thereof and its other end attached to the spirally slotted guide tube at its upper end.

3. The subject mattei' of claim l and a lead follower disposed in the lead clutch and also provided with an oilfset portion extending laterally through an opening in said lead clutch and engaging the slots of the longitudinally slotted feed tube and the spirally slotted guide tube.

4. The subject matter of claim 1 wherein the lead clutch is bowed slightly to obtain the necessary frictional engagement of the lead clutch in the longitudinally slotted feed tube.

5. The subject matter of claim 1 wherein the spirally slotted guide tube is provided at its upper end with limiting means cooperating with a xed part of said tubular body to limit the nward axial movement of said tube when the same is depressed.

6. The subject matter of claim 5 wherein the limiting means is carried by an actuating tube xed to the upper end of said spirally slotted guide tube.

7. The subject matter of claim 5 wherein the spring means comprises a torsion spring. having one end fixed to the tubular body at the tapered end thereof and its other end attached to the spirally slotted guide tube at the I upper end thereof.

REYNOLD B. JOHNSON.

, REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 338,332 Appleby Mar. 23, 1886 364,303 Sachs June 7, 1887 387,042 Bohren July 31, 1888 1,398,955 Anderson Dec. 6, 1921 1,568,951 Ballou Jan. 4, 1926 1,864,038 Barberon June 21, 1932 1,869,198 Keeran July 26, 1932 2,026,815 Barker Jan. 7, 1936 

